Coating aids for hydrophilic colloid layers of photographic elements



United States Patent 0 3,539,352 COATING AIDS FOR HYDROPHILIC COLLOID LAYERS 0F PHOTOGRAPHIC ELEMENTS William J. Knox, Jr., Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Feb. 27, 1968, Ser. No. 708,483 Int. Cl. G03c J/04 U.S. Cl. 96-1145 17 Claims ABSTRACT OF THE DISCLOSURE Hydrophilic colloid layers of a photographic element, e.g., emulsion layers, protective gelatin coats, filter layers, film backings, gelatin subs and the like, are coated on the film support as aqueous dispersions containing minor amounts of a coating aid which is a 2-(aliphatic hydrocarbon)-1-(ethyl-beta-oxipropanoic acid) imidazoline. These compounds also function to prevent wandering of mordanted dyes between layers in color recording elements.

This invention relates to photography and particularly to improvements in photographic recording elements and in methods of making such elements.

Most photographic recording elements comprise one or more layers of hydrophilic colloid coatings, for example, one or more gelatin-silver halide emulsion layers, gelatin subbings, gelatin overcoats, and various other layers comprising gelatin or other hydrophilic colloid vehicle which can also contain other ingredients such as dyes, dye precursors, incorporated developers, color processing ingredients, antistatic agents, antihalation agents, hardeners, nucleating agents, etc. In most instances, these layers are coated as a melt, a liquid suspension or a solution and then chill-set or dried, or both, forming a continuous coated layer.

Coating aids have been used for many years to improve coated hydrophilic colloid layers in photographic recording elements. The best-known and most widely used coating aid has been saponin, a natural organic compound derived from quillaia bark. Being of natural origin, saponin is subject to inconsistencies in composition depending upon the source, methods of extraction, etc. With development of modern, high-speed coating techniques and modern improvements in hydrophilic colloid layers, saponin has become not so universally favored as a coating aid for all uses and synthetic coating aids have been sought for some applications in the emulsion coating art. Although many synthetic surface active agents have been made available in recent years, only rarely has one been found among these that would be suitable as a coating aid for hydrophilic colloid layers in making photographic recording elements.

One of the objects of the present invention is to provide improved coating aids for use in coating of hydrophilic colloid layers in photographic recording elements. This new class of coating aids improves uniformity of coating of hydrophilic colloid layers onto photographic supports, such as film and paper supports, and enables repellency free coatings to be obtained. These coating aids are especially suited for use in modern high-speed coating techniques. These coating aids tend to reduce surface roughness of hydrophilic colloid layers in which they are used. They are found to improve wettability and permeability of the layer by photographic processing solutions when such solutions are applied to the finished coatings. The coating aids are compatible with the photographic ingredients of most photographic recording elements and with most photographic developer solutions and especially 1 have found this class of coating aids to be compatible when used in mordanted dye layers in which many otherwise suitable coating aids have been found to have the undesirable tendency to cause wandering of the mordanted dyes. In short, this class of surface active agents has met exacting requirements as a coating aid for a variety of hydrophilic colloid layers in modern photographic elements and for modern methods of making such elements, and the coating aids are especially useful in coating layers containing mordanted dyes.

In accordance with the present invention, I employ, as a coating aid in the various types described above of hydrophilic colloid layers in photographic recording elements and the like, substituted imidazolines having the following formula:

wherein R is an aliphatic hydrocarbon radical containing 7 to 21 carbon atoms as, for example, the saturated and unsaturated hydrocarbons derived from fatty acids. Compounds of this formula can be described as 2-(aliphatic hydrocarbon) -1-(ethyl-beta-oxipropanoic acid) imidazoline. Compounds of this class generally have characteristics typical of amphoteric compounds. The hydrogen ion concentration of the solution governs their behavior in a solution to some extent. In strongly acid solution, cationic behavior predominates, characterized by attraction of the molecules to negatively charged surfaces. In alkaline solution the predominant effect is anionic behavior. A group of compounds of the formula described above are available commercially, bearing the trade name Monateric, from Mona Industries, Inc., Patterson, NJ. The following specific Monaterics have been obtained from this source and are found useful in accordance with the invention.

Trade name R Origin of R Mol. wt.

Monateric C-A 0 -01 Coconut fatty acid 360 Mouaterrc L-A 11 Laurie acid 340 Monateric O-A C11 Oleic acid-.-" 417 Monatene S-A 015-11 Stearic acid 410 EXAMPLE 1 A conventional silver halide-gelatin aqueous photographic emulsion is prepared and coated on a baryta coated paper support by conventional hopper coating apparatus at a coating speed of 50 feet per minute. A clear gelatin layer is coated simultaneously over the wet emulsion layer using a multilayer hopper of the type described in Russell U.S. Pat. No. 2,761,791, patented Sept. 4, 1956. These are control coatings containing no coating aids. This emulsion corresponds generally to a conventional projection speed black-and-white printing emulsion except the conventional coating aids are omitted. Control coatings containing no coating aids are compared with coatings of the same emulsion and the same gelatin overcoat composition to which have been added varying amounts of the Monateric OA composition described above as a coat ing aid prior to coating. Coating runs are made using this coating aid in the emulsion layers and in the overcoat layers in various concentrations as tabulated in Table I bclow. Also shown in Table I are results obtained from developer spread tests, coeflicient of friction tests, and repellency counts made on each of the finished dry photographic papers prepared as described. Developer spread is an empirical test of wettability and permeability of the coatings and is measured by delivering 1 milliliter of conventional liquid photographic solution to a point on the surface of the coating and measuring the area developed after 30 seconds by horizontal spreading of the developer on the film surface. This is sometimes called an Air Bell test. The coefiicient of friction of the coated surface is measured against uncoated paper by conventional testing apparatus and is expressed in conventional terms. Repellencies are defects in the coatings. The number or" repellencies shown in Table 1 for each sample is measured by counting the number of visible repellencies on a typical 7 /2 square feet area taken from each test sample. Bright repellencies are small uncoated areas which usually result from imperfect adhesion of the coating to the support, usually caused by an unwetted area on the support or sometimes by an oily inhomogeneity in the emulsion melt. A dull repellency is a defect usually caused by some inhomogeneity at the interface between coated layers, in this instance, between the gelatin layer and emulsion layer. These may result from interaction of incompatible components in the respective layers.

TABLE I Monateric O-A concentration Goetfi- Ropellencies Gm./lb. GnL/lb. Develcient 7.5 it. wet emulwet overoper of Sample sion coat spread friction Bright Dull Control..." 4. 9 0. 37 3 0. (J 0.5 10. 70 0. 38 0.13 0.5 9. 62 0. 25 0. 5 10. 70 0. 24 0. 5 0. 5 12. 60 0.25 l

1 None.

Comparable results are obtained with other Monaterics listed above.

Similar tests using the control with conventional coating aids such as saponin in the wet overcoat show no repellencies, developer spread intermediate between the control and sample 1, and coefficient of friction higher than the control.

EXAMPLE 2 A multilayer color film is prepared as described in Example 16 of Carroll et al. U.S. Pat. No. 2,944,900, patented July 12, 1960, except a yellow filter layer of the following description is used instead of the Carey Lea silver blue light filter.

A gelatin, basic mordant-acid dye solution is prepared containing 454 parts gelatin, 227 parts basic fordant of the kind described in Minsk U.S. Pat. No. 2,882,156, patented Apr. 4, 1959, 75.6 parts yellow sulfonated benzoxazole pyrazolone dye and Water to make a 1.4% gelatin solution. Monateric L-A, HCl is added to the coating melt at a concentration of 0.89 gram per pound of melt.

The finished film is exposed on a sensitometer and processed as described in Example 2 of U.S. Pat. 2,944,900. No loss in speed is observed. With conventional coating aids or no coating aids a substantial loss of speed is observed, caused by wandering of the yellow dye into the emulsion layers. The present element is stable against dye wandering even after incubation for 7 days at 125 F 50% relative humidity.

Coating aids of the present invention will be useful generally for coating hydrophilic colloid layers of various kinds used in photographic films, plates, papers and the like. Satisfactory colloids which can be used for this purpose include any of the hydrophilic colloids generally employed in the photographic field, including, for example, gelatin, colloidal albumin, polysaccharides, cellulose derivatives, synthetic resins such as polyvinyl compounds, including polyvinyl alcohol derivatives, acrylamide polymers and the like. In addition to the hydrophilic colloids, the vehicle or binding agent can contain hydrophobic colloids such as dispersed polymerized vinyl compounds, particularly those which increase the dimensional stability of photographic materials. Suitable compounds of this type include water-insoluble polymers of alkyl acrylates or methacrylates, acrylic acid, sulfoalkyl acrylates or methacrylates and the like. Such layers can be functional in the photographic element as sub-layers, protective overcoats, antihalation or antistatic backings, filter layers, dye bearing layers, various emulsion layers, diffusion transfer receiving layers, reflective layers, or for other functions in a photographic element. The coating aids can be used in silver halide emulsion layers of various compositions as, for example, silver chloride, bromide, bromoiodide, chlorobromide, etc., emulsions including high speed silver halide emulsions such as emulsions sensitized with sulfur selenium, tellurium and/ or noble metal compounds such as gold sensitizers. They are especially useful for multiple layer coating of emulsion and protective layers simultaneously on paper support, and for coating of mordanted dye layers in color photographic elements. Elements comprising colloid layers containing the coating aids of this invention can be negative films, reversal films, medical X-ray films, black-and-white or color films or printing papers, or any of the other types of recording elements that comprise hydrophilic colloid coatings. Emulsion layers coated with the coating aids of the invention can be emulsion sensitized by any of the known techniques using any of the various chemical and spectral sensitizers and other adjuvants employed in emulsion making. The coating aids can be used for coating on any suitable support. The coating aids can be used in one or several coated colloid layers of an element. Supports suitable for receiving the colloid layers include cellulose nitrate, cellulose acetate, polyvinyl acetal, polystyrene, polyethylene terephthaate film, baryta coated papers, polyethylene or other polyolefin coated papers, and the like.

Colloid layers coated with coating aids of the present invention can also comprise any of the various suitable hardeners such as chrome alum, aldehydes such as formaldehyde or mucochloric acid, aziridine hardeners, derivatives of dioxane, oxypolysaccharides such as oxy starch or oxy plant gums, etc. Layers coated with the coating aids can contain or can be coated in elements containing other additives such as lubricants, e.g., long chain fatty acids, silicone resins, N-alkyl-beta-aminopropionates, palmityl palrnitate, or containing various plasticizers. Elements comprising coating aids of the invention can be processed in any of the various developing and finishing processes known for producing finished photographs. Layers coated with these coating aids can contain or be incorporated in elements containing incorporated developers such as polyhydroxybenzenes, aminophenols, B-pyrazolidones, including dye developers of the type described in Rogers U.S. Pat. No. 2,983,606 pap ented May 9, 1961.

The coating aids can be used in concert with other suitable wetting agents, which can be included in the same layer with the present coating aids, or in another layer of an element comprising several layers. Such other wetting agents can include non-ionic, cationic, anionic, or other amphoteric types, for example, polyoxyalkylene derivatives, amphoteric amino acid dispersing agents such as sulfobetaines and the like. Suitable other wetting agents are described in U.S. Pat. 2,600,831 patented June 17, 1952; 2,271,622 and 2,271,623 patented Feb. 3, 1942; 2,275,727 patented Mar. 10, 1942; 2,787,604 patented Apr. 2, 1957; 2,816,920 patented Dec. 17, 1957', 2,739,891 patented Mar. 27, 1956; and British Pat. 1,022,878.

The coating aids of the invention can be used in colloid layers containing, or in layers of elements comprising other layers containing, emulsion stabilizers or antifoggants, particularly noble metal compounds described in U.S. Pats. 2,566,245, 2,566,263, and 2,597,856; triazaindolines described in U.S. Pats. 2,444,605, 2,444,606, and 2,444,607, or containing speed-increasing materials, absorbing dyes and the like, or containing as sensitizers alkylene oxide polymers which can be employed alone or with other materials such as quaternary ammonium salts as disclosed in U.S. Pat. 2,886,437 or with mercury and nitrogen compounds as described in U.S. Pat. 2,- 751,299.

Although the invention has been described in detail with particular reference to preferred embodiments thereof, variations and modifications can be effected within the spirit and scope of the invention as described hereinbefore and as defined in the appended claims.

I claim:

1. In a method of coating a film of aqueous solution comprising hydrophilic colloid, the improvement which comprises incorporated into said solution as a coating aid, a minor amount of a 2-(aliphatic hydrocarbon)-1- (ethyl-beta-oxipropanoic acid)imidazoline, said aliphatic hydrocarbon containing 7 to 21 carbon atoms.

2. An aqueous hydrophilic colloid solution comprising as a coating aid therein, a minor amount of a 2-(aliphatic hydrocarbon)-1-(ethyl-beta-oxipropanoic acid)imidazoline, said aliphatic hydrocarbon containing 7 to 21 car bon atoms.

3. An aqueous hydrophilic colloid solution comprising as a coating aid therein a 2-(aliphatic hydrocarbon)-l- (ethyl-beta-oxipropanoic acid)imidazoline wherein said aliphatic hydrocarbon contains 7 to 21 carbon atoms.

4. An aqueous hydrophilic colloid solution defined by claim 3 wherein said hydrophilic colloid is gelatin.

5. A photographic silver halide emulsion comprising silver halide grains dispersed in an aqueous hydrophilic colloid solution defined by claim 3.

6. A photographic recording element comprising at least one hydrophilic colloid layer which comprises a minor amount of a 2-(aliphatic hydrocarbon)-1-(ethyl beta-oxipropanoic acid)imidazoline wherein said alkyl contains 7 to 21 carbon atoms.

7. A photographic element defined by claim 6 wherein said 2-(aliphatic hydrocarbon)-1-(ethyl-beta-oxipropanoic acid)imidazoline occurs in a gelatin coat overlying beta-oxipropanoic acid)imidazoline is a color-filter layer 8. A photographic element defined by claim 6 wherein said 2-(aliphatic hydrocarbon)-1-(ethyl-beta-oxipropanoic acid)imidazoline occurs in a gelatin coat overlying a photographic silver halide emulsion layer.

9. A photographic element defined by claim 6 wherein said 2-( aliphatic hydrocarbon)-1-(ethyl-beta-oxipropanoic acid)imidazoline occurs in a photographic silver halide emulsion layer and also occurs in a gelatin coat overlying said emulsion layer.

10. A photographic element defined by claim 6 wherein said 2-(aliphatic hydrocarbon)-1-(ethyl-beta-oxipropanoic acid)imidazoline occurs in a hydrophilic colloid layer that contains a mordanted dye.

11. A photographic element defined by claim 10 wherein the hydrophilic colloid is gelatin.

12. A photographic element defined by claim 10 wherein said layer containing 2-(aliphatic hydrocarbon)-1-(ethylbeta-oxipropanoic acid)imidazoline in a color-filter layer of a photographic multicolor recording element.

13. A photographic element defined by claim 10 wherein said dye is a sulfonated benzoxazole pyrazolone dye.

14. An aqueous hydrophilic colloid solution defined by claim 2 wherein said aliphatic hydrocarbon radical is the aliphatic hydrocarbon radical of coconut oil fatty acid.

15. An aqueous hydrophilic colloid solution defined by claim 2 wherein said aliphatic hydrocarbon radical is the aliphatic hydrocarbon radical of lauric acid.

16. An aqueous hydrophilic colloid solution defined by claim 2 wherein said aliphatic hydrocarbon radical is the aliphatic hydrocarbon radical of oleic acid.

17. An aqueous hydrophilic colloid solution defined by claim 2 wherein said aliphatic hydrocarbon radical is the aliphatic hydrocarbon radical of stearic acid.

References Cited UNITED STATES PATENTS 2,847,418 8/1958 Steele 106-135 3,211,555 10/1965 Mory 96114.5

NORMAN G. TORCHIN, Primary Examiner J. R. HIGHTOWER, Assistant Examiner U.S. Cl. X.R. 

